1. Field of the Invention
The present invention relates to a recording medium driving apparatus driving a recording medium such as a MD (mini-disk). More particularly, the present invention relates to a recording medium driving apparatus in which deformation of a turntable or a recording medium itself upon insertion of the recording medium in an abnormal state is prevented.
2. Description of the Related Art
FIG. 9 is a principle diagram illustrating the internal structure of a conventional recording medium driving apparatus.
The recording medium driving apparatus A shown in FIG. 9 is, for example, a MD (mini-disk) player which records and/or reproduces information on a recording medium such as a photomagnetic disk housed in an external case such as a cartridge C.
Reference numeral 1 represents an enclosure of the MD player (recording medium driving apparatus), and this enclosure 1 has an insertion port 2 provided on the right end side thereof. A holder 3 is provided in the enclosure 1, and an opening 3a of the holder 3 faces the foregoing insertion port 2. In the standby state shown in FIG. 9, the holder 3 is at an elevated position in the Z1 direction in the drawing.
A driving section 4 is provided below (Z2 direction) the holder 3 and is elastically supported by an elastic supporting member such as a damper (not shown). As a result, even when mounted in an automobile, vibration from the automobile body does not directly act on the driving section 4. The driving section 4 is provided on a driving base 5, and there is provided a spindle motor Ms that imparts a rotational force to a photomagnetic disk in the cartridge C. A recording/reproducing head (not shown) conducting recording on and/or reproduction from the MD is provided so as to permit scanning in the radial direction of the photomagnetic disk. A turntable Ta is firmly secured to the leading end of a rotation shaft Ma of the spindle motor Ms by a fixing means such as pressure-insertion.
A locator pin 6 projecting in the Z1 direction in the drawing is provided at an end of the driving base 5. When the MD is inserted in the normal direction and posture into the holder 3, a positioning hole 3b formed in the cartridge C faces the locator pin 6. A detection switch 7 is provided on the driving base 5 so as to permit detection of end of loading of the MD in the driving section 4.
The recording medium such as a MD is inserted into the recording medium driving apparatus through the insertion port 2 and held in the holder 3 via the opening 3a. The holder 3 is brought down in the Z2 direction by a lifting member (not shown). When the MD is inserted in the normal direction and posture into the holder 3, a clamping plate Cp of the photomagnetic disk exposed to the bottom surface of the MD is attached to the turntable Ta in the aforementioned descending operation. At this point, the locator pin 6 enters into the positioning hole 3b formed in the bottom surface end of the cartridge C of the MD. The bottom surface of the holder 3 of the cartridge C presses an actuator of the detection switch 7, thus permitting detection of the loading of the MD in a normal condition.
Upon discharge of the MD, the holder 3 is lifted by the lifting member in the Z1 direction in the drawing, and the clamping plate Cp leaves the turntable Ta. At this point, the locator pin 6 escapes from the positioning hole 3b, and the pressure on the detection switch 7 is released. When the holder 3 reaches the elevated standby position, the MD in the holder 3 is discharged by discharge means not shown from the insertion port 2 to outside the enclosure 1.
The above-mentioned recording medium driving apparatus has, however, the following problems.
The recording medium such as a MD may sometimes be inserted into the holder in an abnormal direction or posture including an upside-down (reversed) state or with wrong longitudinal and transverse sides. In such a case, in the MD player, it is impossible to detect the insertion of the MD in an abnormal direction or posture upon insertion of the MD into the holder 3, and the holder 3 descends in the Z2 direction just as in a normal insertion. However, when the MD is inserted into the holder 3 in an abnormal state, the turntable Ta does not positionally agree with the clamping plate Cp of the photomagnetic disk in the cartridge C.
Therefore, when the holder 3 descends in this abnormal insertion state, the turntable Ta and the clamping plate Cp do not face each other. For example, the outer surface of the cartridge C comes into contact with the turntable Ta, thus pressing down (in the Z2 direction) the turntable Ta. If, in this state, the detection switch 7 cannot detect the completion of loading of the MD within a prescribed period of time, the MD is judged to have been inserted erroneously (in an abnormal direction or posture), and as a result, the holder 3 goes up and the MD is discharged. However, a strong pressing force acts onto the turntable Ta during descent of the holder 3 as described above, resulting in problems of deformation of the turntable Ta itself, or if the turntable Ta and the rotation shaft Ma are not firmly secured, a positional shift of the turntable Ta in the axial direction of the rotation shaft Ma.
In order to prevent occurrence of these problems, it is necessary to form the turntable Ta from a metal to prevent deformation of the turntable Ta itself, and firmly secure the turntable Ta and the rotation shaft Ma by fabricating the inside diameter of a center hole of the turntable Ta with high accuracy and pressure-driving this center hole onto the rotation shaft Ma, thereby preventing a positional shift of the turntable Ta.
However, a structure in which the turntable Ta made of a metal and the rotation shaft Ma of spindle motor Ms are pressure-driven requires high-accuracy operations such as cutting, piercing and pressure-fabrication of the turntable Ta, leading to a higher cost. When, after pressure-driving the turntable Ta onto the rotation shaft Ma, the spindle motor Ms is fixed in a state in which the rotation shaft Ma is inserted sideways into a notch in the driving base 5, it is necessary to pierce, in the turntable Ta, holes Ta1 and Ta2 for inserting a screw tightening tool (driver) for tightening screws 8 into fixing holes M2 formed in the spindle motor Ms. Cutting these holes Ta1 and Ta2 in the turntable Ta results in a further higher fabrication cost.
When the holder 3 having the MD in an abnormal state descends, the positioning hole 3b formed in the cartridge C does not face the locator pin 6. As a result, the lower surface of the cartridge C hits the locator pin 6 along with descent of the holder 3, so that the cartridge C is strongly pressed against the locator pin 6. The cartridge C may therefore deform or suffer damage.